The old clich that idle hands are the devil's workshop dates back at least to Chaucer, but never have our hands been as occupied as they are today. Email, Internet-everywhere, the 24-hour office sometimes it seems we ll do anything to avoid an idle moment. Yet, we don t like to exert ourselves without reason. Stripped of purpose, humans tend toward laziness. We re both disposed to idleness and repulsed by it.

So do we prefer to be active or idle? Which makes us happier?

A recent study in Psychological Science takes a look at these questions, and the researchers, Christopher K. Hsee and Adelle X. Yang of the Booth School of Business, University of Chicago, and Liangyan Wang of the Antai School of Management, Shanghai Jiaotong University, came up with some clever ways to get at some answers.

In the first of two experiments, the researchers looked at how people decide whether to be idle and how that decision makes them feel afterward. Ninety-eight students at a large public university were instructed to fill out multiple surveys about their school and that they could do nothing else during the course of the experiment. However, after the first survey was over, they were told that the next one would not be ready for 15 minutes. They were to hand in their first survey at one of two designated locations: one right outside the exam room, and one a 12-minute-roundtrip walk away.

The experiment was run twice. In both versions, the students were told they d get a piece of candy, as a token of appreciation for their time, when they handed in their survey. In one version, they were told that there was a different candy at the far-away test drop-off (milk chocolate at one location, dark chocolate at the other). The type of candy offered at each location was randomized; and pre-testing indicated that the students saw each type of candy as equally desirable.

Nonetheless, something odd happened: When the same candy was offered at both locations, only about 30% of the participants walked to the far location; but when different candies were offered, nearly 60% of the participants chose to take the walk.

Again, the candies (randomly offered and equally appealing) shouldn t have been able to affect the students decisions. Still, given even the thinnest justification for occupying themselves as opposed to sitting idle for 15 minutes in an exam room the students jumped at it.

What s more, the students who occupied themselves by going to the farther-away location seemed to have made themselves happier. At the end of the 15 minutes, all the students were given a survey asking them to rate their happiness over the last 15 minutes on a scale of 1 to 5. Participants who d made the trip, in both versions of the experiment, reported a happiness score at least one point higher than those who had stayed put. Busy was happier than idle.

Another odd thing about how the students behaved was that, absent an excuse to stay busy, they declined to do so even though it seems they knew that boredom would make them unhappy. In another survey of another group of students, the researchers asked them to predict who would be happier in their experimental scenario the people who stayed busy or the ones who stayed idle. Roughly two-thirds guessed correctly.

So, we know boredom makes us unhappy, yet we seem to require a reason not to be idle.

Why do we need this justification? The authors speculate that the root is evolutionary as with any animal, most humans once needed to conserve energy to survive. In modern society, though, we have energy to burn. That tension between an instinct to conserve and a knowledge that we no longer have to may be at the heart of our conflicting emotions toward idleness.

What does this mean for the average person? The authors suggest that homeowners might increase the happiness of their idle housekeepers by letting in some mice. The suggestion is silly, but the insight is real. Some architects have already taken it to heart: Airports have long been designed to make you walk quite a way to baggage claim, so that you don t end up standing beside a carousel long before your bags have even had time to make it out of the luggage hold.

It may sound paternalistic, but chances are it s saved you some serious annoyance. And it s left the devil less with which to work.